The interaction of nuclear and organelle genomes will be examined with respect to the inheritance and functional properties of chloroplast and cytoplasmic ribosomal RNA and proteins. Biochemical and genetic analyses using several species of Nicotiana and their F1 hybrids will be performed in order to decide whether chloroplast DNA carries genes which uniquely code for any of the proteins or the RNA nucleotide sequences of chloroplast ribosomes and to determine if any of the genes involved are also shared with those coding for cytoplasmic ribosomal macromolecules.